Crystalline molecular sieves are widely used as catalysts in the industry since they possess catalytically active sites as well as uniformly sized and shaped micropores that allow for their use as shaped selective catalysts in, for instance, oil refining, petrochemistry and organic synthesis. However, due to the pore size constraints, the unique catalytic properties of zeolites are limited to reactant molecules having kinetic diameters below 10 angstroms.
A series of mesoporous molecular sieves with increased diameters were disclosed in U.S. Pat. Nos. 5,057,296 and 5,102,643. These molecular sieves overcome the limitation of microporous zeolites and allow the diffusion of larger molecules. These materials, however, are amorphous solids. Amorphous silica-aluminas have much weaker acid sites than zeolites and thus do not exhibit the spectacular catalytic properties of acidic zeolites. Moreover, their hydrothermal stability is low and, as a consequence, their industrial use as catalysts is very limited
Improved metal-containing colloidal compositions that possess the stability to undergo further processing to mesoporous ZSM-5 material (“meso-ZSM-5”) have commercial significance.